1. Field of the Invention
The present invention relates to a slider for a magnetic head and a magnetic recording drive and, more particularly, to a slider for a magnetic head which is able to fly over a surface of a magnetic recording medium and to a magnetic recording drives equipped with the slider for magnetic head.
2. Description of the Prior Art
In the magnetic disk drive, a CSS (contact start and stop) scheme in which the slider for magnetic head starts in contact with the magnetic disk and again comes into contact with the magnetic disk at the time of stop has often been adopted.
In the magnetic head flying type magnetic disk drive, higher recording density has been intended to promote miniaturization.
Accordingly, a flying height of the magnetic head (electromagnetic transducer) from the magnetic disk, i.e., a spacing is prone to be reduced. If the flying height is lessened, there is necessity of preventing contact between the magnetic disk and the magnetic head by reducing surface roughness of the magnetic disk.
The slider for magnetic head employing the CSS scheme comes into contact with the magnetic disk when it is stopped while it flies over the surface of the magnetic disk because of operation of air flow caused by the rotation of the magnetic disk, i.e., based on the principle of dynamic kinetic air pressure bearing by fluid lubrication.
In the magnetic disk drive employing the CSS scheme, as unevennesses of the surface of the magnetic disk are reduced to thus lower surface roughness, the slider in the flying state does not come into contact with the surface of the magnetic disk.
However, if the surface roughness is lowered, contact areas between the slider and the magnetic disk are enhanced when the magnetic disk is in the stop state, potentially be causing the slider and the magnetic disk to stick to each other.
If the slider and the magnetic disk are stuck tightly together, a suspension for supporting the slider could be destroyed upon staring rotation of the magnetic disk. Hence, it becomes difficult for the slider to fly over the magnetic disk normally.
In order to reduce such problem, it has been set forth in Patent Application Publications (KOKAIS) 63-37874 and 4-28070, for example, to reduce contact areas between the magnetic disk and the slider by providing a plurality of projections on kinetic air pressure bearing surfaces (rail surfaces) of the slider for the magnetic head opposing to the magnetic disk.
Diameter of the projections of the slider must be lessened to reduce the contact areas between the slider and the magnetic disk as flatness of the surface of the magnetic disk is improved.
However, if diameters of the projections are lessened, pressure applied to a unit area of the projection becomes high. In addition, a situation could readily occur in which a part of plural projections do not come into contact with the surface of the magnetic disk, because of deviation of a center of gravity in the stopped state of the slider causing the rail surfaces to twist.
As a result, since pressure applied to a part of the projections is increased higher than a design value in the stopped state projections are quickly worn-out, and the durability of the magnetic head is decreased.
Still further, although the height of the projections must be selected to a height not to affect the fly of the slider, e.g., be lowered to about 30 nm, the height is selected on the substantially in the same order as a finished crowning amount of the rail surfaces of the slider.
In this case, since rail surfaces positioned at locations other than the projections come into contact with the magnetic disk, the meaning of the projections provided to prevent such stick is lost.